Magnetveld

Magnetveld is the Dutch term for magnetic field, a vector field that describes the magnetic influence of electric currents and magnetic materials. At each point in space the magnetveld is represented by a vector whose direction indicates the force that would act on a north‑seeking pole and whose magnitude gives the strength of that force per unit pole strength. In the International System of Units the magnetic flux density B, often called the magnetveld, is measured in teslas (T) or, for weaker fields, in gauss (1 G = 10⁻⁴ T).

The fundamental relation linking the magnetveld to electric currents is expressed by Ampère’s law and, in differential form, by ∇ × B = μ₀ J + μ₀ε₀ ∂E/∂t, where J is the current density, μ₀ the permeability of free space and E the electric field. For static situations the magnetveld can be derived from a magnetic scalar potential, while in dynamic regimes it obeys Maxwell’s equations together with the electric field.

In geophysics the term magnetveld is used to refer to the Earth’s geomagnetic field, a large‑scale magnetveld generated by the motion of molten iron in the outer core. This planetary magnetveld shields the atmosphere from solar wind, guides compass navigation and is the basis for magnetotelluric surveys that image subsurface electrical conductivity.

Measurement of magnetvelden employs devices such as fluxgate magnetometers, optically pumped magnetometers and superconducting quantum interference devices (SQUIDs). These instruments enable applications ranging from space weather monitoring and mineral exploration to medical imaging techniques like magnetic resonance imaging (MRI). The concept of magnetveld underlies much of modern physics, engineering and Earth science.